According to one embodiment, a semiconductor light emitting device includes: semiconductor layers; a multilayered structural body; and a light emitting portion. The multilayered structural body is provided between the semiconductor layers, and includes a first layer and a second layer including In. The light emitting portion is in contact with the multilayered structural body between the multilayered structural body and p-type semiconductor layer, and includes barrier layers and a well layer including In with an In composition ratio among group III elements higher than an In composition ratio among group III elements in the second layer. An average lattice constant of the multilayered structural body is larger than that of the n-type semiconductor layer. Difference between the average lattice constant of the multilayered structural body and that of the light emitting portion is less than difference between that of the multilayered structural body and that of the n-type semiconductor layer.